Since plastic lenses are light, not easily cracked, and can be stained in comparison to inorganic lenses, plastic lenses have been rapidly distributed as optical elements such as eyeglass lenses and camera lenses. Hitherto, various resins for lenses have been developed and used, and, among these resins, a typical example is a thiourethane-based molded product obtained using a polymerizable composition including a polyisocyanate and a thiol compound. The thiourethane-based molded product is one of optical materials having high refraction, low dispersion, and excellent impact resistance (refer to Patent Documents 1 to 4).
On the other hand, in the related art, the adverse effects due to exposure of the eye to ultraviolet rays having a wavelength of 380 nm to 400 nm have been an issue. Furthermore, in recent years, effects on the eye such as eye strain or pain by blue light having a wavelength of about 420 nm included in light emitted from natural light, liquid crystal displays of office equipment, or displays of portable devices such as a smart phone or a mobile phone have been an issue, and thus, it is required to reduce the amount at which the eye is exposed to light from ultraviolet rays to blue light having a wavelength of about 420 nm.
The effects of blue light having a wavelength of about 420 nm on the eye are described in Non-Patent Document 1. In Non-Patent Document 1, damage of retinal nerve cells (cultured retinal nerve R28 cells of a rat) due to irradiation with blue LED light having different peak wavelengths of 411 nm and 470 nm is verified. As a result, while irradiation (4.5 W/m2) with blue light having a peak wavelength of 411 nm causes cell death of retinal nerve cells within 24 hours, in blue light having a peak wavelength of 470 nm, it is shown that changes in the cells do not occur even in the case of the same amount of irradiation. That is, it is shown that it is important to suppress the exposure of blue light having a wavelength of 400 nm to 420 nm to prevent eye disability.
In addition, there is concern that eye strain or stress occurs due to exposure of irradiation with blue light to the eye for a long period of time, and this is considered to be a factor that causes age-related macular degeneration (refer to Non-Patent Document 1).
In Patent Documents 5 to 7, a plastic lens including an ultraviolet absorber such as a benzotriazole-based compound is disclosed.
A thiourethane-based molded product configuring a plastic lens is obtained by curing a polymerizable composition which has a polyisocyanate and a thiol compound as main components, and various thiol compounds have been proposed in the related art. In Patent Documents 8 and 9, it is described that by using a thiol compound and a polyisocyanate, a thiourethane-based molded product having a high refractive index and low dispersion is obtained.
In the documents, as a thiol compound, a thiol compound (polythiol A3) including 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane (hereinafter, referred to as a polythiol B) or 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane (polythiol A1), 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane (polythiol A2), and 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane (hereinafter, one of the polythiols A1, A2, A3 or a mixture of two or more kinds thereof is referred to as a polythiol A) is exemplified.
The values of optical properties such as a refractive index and an Abbe number of the thiourethane-based molded product obtained from the polythiol A and a polyisocyanate are substantially the same as those of the thiourethane-based molded product obtained from the polythiol B and the same polyisocyanate (Patent Document 9).